Reflecting Room Brightness in Materials with Apple Vision Pro

This article is a translated version of my original post on Qiita. Original (Japanese): https://qiita.com/segur/items/1387a4a406b507c0b78a

Reflecting Room Brightness in Materials with Apple Vision Pro

In visionOS, using the URP Lit shader allows material brightness to change based on the room's light level. This feature is available on Apple Vision Pro as well—convenient indeed!

In a bright room, the Lit shader makes the material appear brighter	In a dark room, the material appears darker

However, when the Lit shader is applied to anime-style avatars, it tends to appear more plastic and unnatural.

Original Toon shader	Significant mismatch with Lit shader

So, I wanted to use a Toon shader in visionOS, but as of April 2024, a suitable Toon shader for visionOS wasn't available.

Using an Unlit shader is another option, but it doesn't adapt to room lighting.

Less mismatch in a bright room with Unlit shader	Significant mismatch in a dark room

Therefore, I decided to create a new shader based on the Unlit shader that accommodates room lighting!

Development Environment

At the time of writing, the development was done in the following environment:

• macOS 14.2.1
• Unity 2022.3.19f1
• PolySpatial 1.1.6
• Xcode 15.3
• visionOS 1.1

Using PolySpatial Environment Radiance to Capture Room Brightness

The Diffuse Radiance output from the PolySpatial Environment Radiance node represents room brightness, including color information!

I created the following ShaderGraph to utilize this feature:

The process is straightforward: multiplying the color information extracted from a texture by the Diffuse Radiance value. This enabled room brightness to be reflected in the material as shown below:

With Diffuse Radiance, the material brightens in a bright room	With Diffuse Radiance, the material darkens in a dark room

Supporting Emission

To address the lack of Emission for eyes, I added the following processing:

The eyes became slightly brighter!

Without Emission	With Emission

This worked well on the actual Apple Vision Pro device!

#AppleVisionPro used to dance 1/8 scale VRM avatar! #栄VP is fun with many acrylic stands! The song is Bibideba!
Thanks to the shader graph reflecting room brightness, discomfort in dark rooms is reduced!
Received well by members present! #VisionPro pic.twitter.com/rHEnF9L6TC

— segur(せぎゅ)@ARエンジニア (@segur_vita) March 30, 2024

Sample Code

The ShaderGraph created for this project is shared here. Feel free to refer to it:

• https://gist.github.com/segurvita/4bd17d7769a51035d3ebd9a834a134d1

OpenUPM

The shader developed here is also available on OpenUPM! Please make use of it:

https://openupm.com/packages/com.segur.poly-spatial-environment-diffuse-shader/

Conclusion

The creation of this article was guided by the following pages. Thank you very much:

• https://docs.unity3d.com/Packages/com.unity.polyspatial.visionos@1.1/manual/PolySpatialLighting.html
• https://qiita.com/from2001vr/items/cdedbecfb91908cef0d7